A private branch exchange (PBX) is a telephone exchange or switching system that serves an organization and performs concentration of central office lines or trunks and provides intercommunication between telephone stations in the organization. The central office lines provide connections to the public switched telephone network (PSTN) and the concentration aspect of a PBX permits the shared use of these lines between all stations in the organization. The intercommunication aspect of the PBX allows two or more stations to establish telephone or conferencing calls between them without using the central office lines.
Hybrid cloud computing relates to a composition of two or more clouds (private, community or public) that remain unique entities but are bound together, offering the benefits of multiple deployment models. Such composition can expand deployment options for cloud services, allowing information technology (IT) organizations to use public cloud computing resources to meet certain needs. By utilizing “hybrid cloud” architecture, companies and individuals are able to obtain degrees of fault tolerance combined with locally immediate usability without dependency on internet connectivity. Hybrid cloud architecture requires both on-premises resources and off-site (remote) server-based cloud infrastructure.